Search

The inaccessibility of walls often does not allow direct measurements of discontinuity surfaces by conventional geological methods and data can only be obtained by statistical methods which cannot be used for deterministic analysis. Photogrammetric techniques are described which can overcome this problem. For faces less than 50 m high pictures can be easily acquired using a reamed bar. The equipment consists of an aluminium structure supporting a sliding device with two spirit levels for horizontal control on which is mounted a digital camera. The system can be used to obtain horizontal cover of the whole versant and shadows can be eliminated by changing the shooting position and focal length. Complete photogrammetric cover cannot be achieved for high slopes, and for slopes up to 300 m an aerostatic polyurethane helium balloon can be employed using equipment consisting of an aluminium frame supporting two digital cameras. The topographic survey of natural or artificial markers is carried out using a laser reflectorless total station, and the point of origin of the survey is measured using a GPS receiver. A software package has been developed to support the procedure. A helicopter can be used at all heights using the same equipment placed under the helicopter body or laterally attached to it. The application of the approach is illustrated by a case study at a marble quarry in the Carrara district in Italy where the economic value of the area required a study of slope instability phenomena., The inaccessibility of walls often does not allow direct measurements of discontinuity surfaces by conventional geological methods and data can only be obtained by statistical methods which cannot be used for deterministic analysis. Photogrammetric techniques are described which can overcome this problem. For faces less than 50 m high pictures can be easily acquired using a reamed bar. The equipment consists of an aluminium structure supporting a sliding device with two spirit levels for horizontal control on which is mounted a digital camera. The system can be used to obtain horizontal cover of the whole versant and shadows can be eliminated by changing the shooting position and focal length. Complete photogrammetric cover cannot be achieved for high slopes, and for slopes up to 300 m an aerostatic polyurethane helium balloon can be employed using equipment consisting of an aluminium frame supporting two digital cameras. The topographic survey of natural or artificial markers is carried out using a laser reflectorless total station, and the point of origin of the survey is measured using a GPS receiver. A software package has been developed to support the procedure. A helicopter can be used at all heights using the same equipment placed under the helicopter body or laterally attached to it. The application of the approach is illustrated by a case study at a marble quarry in the Carrara district in Italy where the economic value of the area required a study of slope instability phenomena.